This invention relates to fuel injection and injectors used in combustible engines. Fuel injectors may be defined as fuel supply devices which provide an intermittent supply of fuel to an intake manifold or cylinder of an engine. Conventional fuel injectors do not generate uniformly sized and distributed drops of fuel. The size and distribution of the fuel drops is significant to ensure complete mixing of air and fuel and, thereby to ensure efficient combustion in a cylinder of an engine. A nonuniform fuel to air mixture, as resulting from conventional fuel injection systems, induces reduced combustion efficiency and degradation of exhaust purification efficiency, both being factors in increasing fuel consumption and increased amounts of exhaust. This invention relates to devices which use ultrasound in dispersing fuel during injection in order to achieve a better dispersion of fuel and more even fuel air mix, resulting in greater efficiency and cleanliness of an engine.